SUMMARY In this application, we propose to acquire an Optima AUC analytical ultracentrifuge with UV/Vis absorbance and Rayleigh interference optics from Beckman Coulter. There are currently no other AUC instruments at the University of Minnesota. The instrument will be housed in the Minnesota Nano Center, a centrally located, shared facility that will ensure availability to a large number of biomedical researchers at the University of Minnesota. Access to this instrument will enable researchers to measure the sizes, shapes and hydrodynamic properties of their molecules of interest, quantify binding affinities and stoichiometries, assay a range of reaction conditions simultaneously in a single experimental run, and quantify molecular or oligomeric heterogeneities. The Optima AUC will enable monitoring of samples either by absorbance at a single or multiple wavelengths, or via interference optics, which can detect molecules that have low absorbance relative to the absorbance of the sample buffer. These features will offer users flexibility in their detection method, thus circumventing the need to chemically modify or otherwise label samples. Acquisition of the Optima AUC will advance the aims of 14 NIH-funded projects and a number of projects funded through other federal or private foundation sources. These projects represent a diverse collection of research goals, including the understanding and treatment of human diseases such as cancer, HIV, neurological disorders, kidney disorders, cardiomyopathy and muscular dystrophy, as well as the optimization of efficient drug delivery systems.